Long-term cultures of murine fetal liver retain very early B lymphoid phenotype.

Abstract

Fetal liver cells from midgestation murine BALB/c embryos were plated onto BAB-14 bone marrow stromal cell-adherent layers. After a 3-5 wk period, cell growth increased and these cells were expanded in number on fresh feeder layers. The cultured fetal liver cells were lymphoid in morphology, 5-20% cytoplasmic Ig-positive, but < 1% surface Ig-positive. Southern blot analysis of the cultured fetal liver cells, as well as cultured bone marrow-derived B cells, demonstrated a population with germline Ig heavy chain loci, possibly representing very early B cell precursors. Abelson murine leukemia virus (A-MuLV) clonal transformants of such cultured fetal liver cells had a phenotypic distribution similar to that seen with fresh fetal liver transformants but distinct from those obtained with the transformation of cultured or fresh bone marrow. All A-MuLV transformants isolated had rearrangements at the .mu. H chain locus of both chromosomes, irrespective of Ig production. Most .mu. H chain producers had at least one rearranged kappa gene locus. These long-term fetal liver cultures provide large numbers of cells for studying events early in the B lymphocyte lineage. The cultured fetal liver cells retained phenotype traits similar to fresh fetal liver B cells and distinctive from bone marrow cells cultured under similar conditions.